Moore, a 25-year FBI veteran who investigated murders around the world before retiring two years ago, has independently researched and analyzed her case for the past year while Knox waited for her appeal.

Knox, 22, has spent nearly three years in an Italian prison since her November 2007 arrest for the murder of her British roommate, Meredith Kercher. Kercher was found sexually assaulted and her throat slashed, her half naked body under a duvet in her bedroom.

Knox and her former Italian boyfriend Raffaele Sollecito were convicted of murder last December after a nearly a year long trial. A third person, Ivory Coast drifter Rudy Guede, whose DNA was found at the crime scene ,was convicted of taking part in the homicide in an earlier trial.

At first, Moore said, he firmly believed Knox was guilty as charged.

"The police said she is. She was arrested," he said. "It just seemed that's the way it was."

Moore, who has never spoken to Knox's family or lawyers, said it was his wife who urged him to look into Knox's case, convinced she was innocent. In November, Moore obtained the crime scene video, autopsy photos and legal documents. He spent weeks poring through them.

His opinion, he said, quickly changed.

"I couldn't figure out why Amanda and Raffaele weren't eliminated on day one as suspects," he said. "I kept thinking the smoking gun would pop up -- and it didn't come. I didn't know why they were in jail."

Initially, Knox said she was at her boyfriend's house the night of the murder. She was arrested days later after an overnight interrogation in which she said she had a vision she was in the kitchen of the cottage she shared with Kercher the night of the murder and heard screams. She has claimed that she became confused and scared because she was bullied, even struck by her interrogators, and recanted the remarks soon after.

The investigation found none of Knox's DNA -- no hair, blood or fingerprints -- in the bedroom where Kercher was murdered.

Prosecutors allege that the murder weapon is a knife found at Sollecito's apartment with Knox's DNA on the handle and Kercher's on the blade.

Moore dismissed the knife evidence, pointing out that Knox often used it to cook. He also said Italian prosecutors were grasping at straws by pointing to what they say is evidence that Knox tried to wash off Kercher's blood in her own bathroom.

"There is no DNA evidence. What they're saying is that whoever killed Meredith cleaned up in Amanda's bathroom. That's all they say," Moore said. "They found Amanda's DNA in her own bathroom? Astounding."

Amanda Knox Awaits Appeal, Hopes for Freedom

Moore said he spent hours watching video of Italian police officials combing through the crime scene and was shocked at what he saw.

"They were doing unsound forensic techniques that lead to cross contamination. Their techniques were horrible," he said. "If you showed that video tape in American court you would have lost more of your evidence."

He also slammed Italian authorities for their initial interrogation of Knox, which he likened to tactics used by "third-world intelligence agencies."